TEST YOURSELF 2.4 Chemistry 9th Chapter 2

TEST YOURSELF 2.4

1. Why do the isotopes of an element have different atomic masses?

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https://partners.inspedium.com/135627-5-1-45.html Ans. The isotopes of an element have different atomic masses because they have different number of neutrons their nucleus.

2. How many neutrons are present in C-12 and C-13?

Ans. C 12 has 6 neutrons and C-13 has 7 neutrons. Number of neutrons in an atom is found by the formula:

Number of neutrons, n = A-Z

• For C-12, n = 126 = 6

• For C-13, n = 13- 6 - 7

3. Which of the isotopes of hydrogen contains greater number of neutrons ?

Ans. There are three isotopes of hydrogen, protium, (TH), deuterium (H) and tritium (H). Tritium has greater number of neutrons (3) in its nucleus.

4. Give one example each of the use of radioactive isotope in medicine and radiotherapy ?

Ans. Isotopes of lodine-131 are used for diagnosis of goiter in thyroid gland. For cancer, affecting within the body, Co-60 is used because it emits strongly penetrating gamma rays.

5. How is the goiter in thyroid gland detected?

Ans. The radioactive isotopes are used as tracers in medicine to diagnose the presence of tumor in the human body. Iodine-131 is used for diagnosis of goiter in thyroid gland.

6. Define nuclear fission reaction?

Ans. A nuclear reaction in which a heavy nucleus splits into smaller parts spontaneously or on impact with another particle. During this process large amount of energy is released

7. When U-235 breaks up, it produces a large amount of energy. How is this energy used ?

Ans. When U-235 breaks up a large amount of energy is released which is used to convert water into steam in boilers. The steam then drives the turbines to generate electricity.

8. How many neutrons are produced in the fission reaction of U-235?

Ans. Three neutrons are produced in the fission reaction of U-235.

9. U-235 fission produces two atoms of which elements?

Ans. The uranium nucleus breaks up to produce Barium-139 and Krypton-94.